Process for producing photographic materials

ABSTRACT

There is disclosed a process for producing a photographic material using a polystyrene film as a support by subjecting a biaxially drawn, surface-roughened polystyrene film to a high frequency electrodeless discharge in a vacuum at a frequency of 13.56 MHz, and then coating an aqueous emulsion or suspension containing gelatin as a binder on the film. The bond strength between the film support and the coating proves superior to those materials in the prior art.

United States Patent Tatsuta et al.

[ 1*Sept. 24, 1974 PROCESS FOR PRODUCING PHOTOGRAPHIC MATERIALS Inventors: Sumitaka Tatsuta; Wataru Ueno,

both of Kanagawa, Japan Fuji Photo Film Co., Ltd., Minami Ashigara-Shi, Kanagawa, Japan Assignee:

Notice: The portion of the term of this patent subsequent to Oct. 10, 1989, has been disclaimed.

Filed: May 12, 1971 Appl. No.: 142,815

Foreign Application Priority Data May 15, 1970 Japan 45-41358 US. Cl 117/34, 117/47 A, 117/93.1 GD,

96/87 R Int. Cl G03c l/78, B44d l/O92 Field of Search 117/47 A, 34, 93.1 GD;

[56] References Cited UNITED STATES PATENTS 3,697,305 10/1972 Tatsuta 117/47 A Primary ExaminerWilliam D. Martin Assistant Examiner-William R. Trenor Attorney, Agent, or Firm-Sughrue, Rothwell, Mion, Zinn & Macpeak [5 7 ABSTRACT 12 Claims, No Drawings PROCESS FOR PRODUCING PHOTOGRAPHIC MATERIALS BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates to a process for producing a photographic material comprising a biaxially drawn, surface-roughened polystyrene film base.

2. Description of the Prior Art Heretofore, baryta paper consisting of paper made from pulp and a coating composed of a kneaded mixture of fine powders of barium sulfate, a small amount of a binder, such as gelatin, and water has been used as a support for a photographic material, such as photographic paper or diffusion transfer process photographic paper. Such support, however, exhibits certain defects, such as shrinkage or expansion with humidity changes, and especially shrinkage after development, prolonged drying time after development, and low resistance to water.

Extensive work has been conducted in an attempt to overcome these difficulties of conventional baryta paper and has led tothe discovery of the present invention.

SUMMARY OF THE INVENTION According to the present invention, there is provided a process for producing a photographic material which comprises contacting a biaxially drawn, surfaceroughened polystyrene film with an active gas generated by a high frequency electrodeless discharge under reduced pressure or in a stream of helium or oxygen under reduced pressure, and thereafter coating an emulsion or suspension containing gelatin as a binder on the polystyrene film so treated.

By the emulsion or suspension containing gelatin as a binder used in the invention is meant an aqueous emulsion or suspension of gelatin prepared by adding silver halides, such as silver chloride, silver bromide, silver chlorobromide or silver iodobromide, photosensitive diazo compounds or a substance which becomes the nucleus of development of an image-receiving material used in the silver halide diffusion transfer photography, with or without other ingredients.

DETAILED DESCRIPTION OF THE INVENTION The biaxially drawn, surface-roughened polystyrene film used in the present invention is obtained by biaxially drawing a film of a polystyrene resin in a conventional manner and subjecting the drawn film to various surface-roughening treatments. The biaxial drawing may be effected simultaneously or in two stages. The roughening of the surface of the drawn polystyrene film is effected, for example, by contacting the drawn film with an organic solvent which dissolves or swells the polystyrene resin, such as tetrahydrofuran, methyl acetate, ethyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl chloride, ethylene chloride, cyclohexane, benzene, and dimethylformamide either alone or in admixture, and then contacting the treated film with water or with an organic solvent, such as methanol or ethanol, which does not dissolve the polystyrene resin and is miscible with the organic solvent used in the aforementioned swelling treatment. The contacting of the film with the solvent is accomplished specifically by immersing the film in the organic solvent, coating the organic solvent on the film by means of a roller coater or brush, or spraying the organic solvent onto the film bymeans of a sprayer. The surface-toughening may also be effected by mechanically rubbing the surface of the film; or incorporating a blowing agent which will evolve a gas by heat into the film in advance thus rendering the entire film cloudy white; or forming a mixture of polystyrene and another material into a film, and then dissolving out the other material selectively from the film. Any of these surfaceroughening methods will be applicable to the process of the present invention.

The polystyrene resin may contain white pigments, such as titanium dioxide, barium sulfate, calcium sulfate, barium carbonate, lithopone, alumina white, calcium carbonate, silica white, laolin, white lead, barite powder, flowers of zinc, talc, aluminum hydroxide and limestone. If desired, colored pigments may also be incorporated in the polystyrene resin. Illustrative of such are yellow pigments, such as chrome yellow and cadmium yellow, various red, orange or blue pigments and mixtures thereof. All of these are well known to those skilled in the art. Whitening or opacification of the film by such methods enables a photographic material produced from this resin to provide an effective picture.

The polystyrene resin is exceptionally superior in water resistance, dimensional stability, and rigidity. Films of polystyrene which have been subjected to the aforementioned treatment have excellent whiteness and translucence, and thus are suitable as supports for photographic materials. On the other hand, such films are hydrophobic and chemically inert, and therefore, a difficulty arises in that when a hydrophilic, gelatincontaining emulsion is coated on the surface of the film, the coated film does not adhere firmly to the polystyrene support. In order to overcome this difficulty, the polystyrene film whose surface has been roughened by the methods described is contacted with the active atoms or molecules of a gas generated by a high frequency electrodeless discharge under reduced pressure or in a stream of an inert gas or oxygen under reduced pressure. The high frequency electrodeless discharge in the present invention is performed by placing the film to be treated in a discharge tube, maintaining the tube under a vacuum of 0.1 mm Hg or less, inducing discharge at a frequency of 13.56 MHz, and maintaining this state; or after the initiation of discharge, introducing oxygen or helium at a flow rate of I00 cc/min. or less, and continuing the discharge. This type of discharge is well known as shown by U.S. Pat. No. 3,415,683 to Coffman et al. We have found that the surface-roughened polystyrene film initially has a contact angle of to against water, but when it is subjected to the electrodeless discharge based on the present invention, its contact angle decreases to 0 to 40. This indicates that the roughened surface of the polystyrene film has been rendered remarkably hydrophilic.

Naturally, a transparent polystyrene film which has not been subjected to such surface-roughened treatment will have a reduced angle of contact of 5 to 30 when subjected to the aforementioned electrodeless discharge, and it will be seen that its surface has been rendered hydrophilic to some extent. However, experiments indicate that film adhesion cannot be obtained between such transparent film and a coating of an emulsion consisting mainly of gelatin formed on the film, in spite of the fact that the electrodeless discharge treatment of the-film results in a marked reduction in the contact angle. When an emulsion consisting mainly of gelatin is coated on the surface of a polystyrene film which has been subjected to a high frequency electrodeless discharge without prior surface-roughening treatment, there is almost no bond strength over a greater part of the interface between the coated film and the polystyrene film support. The coating comes off from the support, and the adhesion is effected only at dotted points. Hence, such polystyrene film is not commercially feasible as a support of a photographic material.

However, when a biaxially drawn polystyrene film whose surface has been roughened is subjected to an electrodeless discharge treatment even for short periods of time, adhesion is effected uniformly in the interface between the treatment surface of the film and a coating of an emulsion containing gelatin. The bond strength exhibits a very high value both in a dry condition and in a wet condition during developing treatment. For example, in a dry condition, the film does not depart from the coating at their interface, and they are bonded so firmly as to cause cohesion and destruction within the film. The cohesion and destruction strength at this time fully meets the bond strength required between the surface of a support of a photographic material and a coating such as a photographic emulsion layer or an image-receiving layer. The bond strength between the support and the coating of the gelatincontaining emulsion obtained above is not reduced even after a long lapse of time.

The atmosphere in which the electrodeless discharge treatment of the present invention is performed does not affect the adhesion between the film support and the coating whether it is air under reduced pressure, a stream of an inert gas, or a stream of oxygen. In any case, the bond strength between a surface-roughened, biaxially drawn polystyrene film support and a coating of a gelatin-containing emulsion or suspension becomes larger than the cohesion and destruction strength of the support itself merely by exposing the film for several seconds to an atmosphere of active gas generated by excitation due to the electrodeless discharge. Satisfactory results are thus obtained. In coating the surface of the polystyrene film which has been subjected to the high frequency electrodeless discharge treatment with a gelatin emulsion, it is sometimes the practice to coat a gelatin solution or dispersion on the surface, and then coat a silver halide emulsion on the coating of the gelatin emulsion as an undercoat. It is the adhesion between the support and the coating formed by the aqueous gelatin solution that the present invention is particularly concered with, and it is not important what is emulsified or suspended in the aqueous gelatin solution. Accordingly, although the claimed invention is limited to the production of photographic materials, the concept of the invention can naturally be applied to other tehnological fields where the adhesion between a surface-roughened biaxially drawn polystyrene film and a gelatin film or a film of a hydrophilic resin is the subject under consideration.

A better understanding of the present invention will be attained from the following examples which are merely intended as illustrative, and not limitative of the present invention.

The tests on the adhesion between the polystyrene film support and the coating were performed by the following methods.

I. Adhesion Test in Dry Condition A sample is prepared by coating an emulsion containing gelatin as a binder on a support of polystyrene film. A 0.14 mm thick cellulose triacetate film is adhered to the coated surface of the sample using an epoxy resin adhesive. This sample is then left to stand for one day at 23C. and a relative humidity of percent. Thereafter, the sample is cut into a rectangular shape having a width of 1 cm and a length of 15 cm. The cellulose triacetate film is peeled off at a pulling rate of 7.38 cm/min. The peel strength is measured by means of a strain gauge. Where the Examples state that the adhesion is good," it means that the sample has a peel strength of 8 g/mm or more which is a bond strength sufficient for use as a photographic material.

2. Adhesion Test in Wet Condition After development, fixing or rinsing when the sample is still in a wet condition. a 0.14 mm thick cellulose triacetate film is adhered to the coated surface of the sample using a cyanoacrylate type adhesive. The peel strength of the sample was measured in this state. Where the Examples state that the adhesion is good, it means that the sample has a peel strength of 2 g/mm or more in the same sense as mentioned in test 1 above.

EXAMPLE 1 A O. 1 mm thick biaxially drawn polystyrene film support was immersed for 3 seconds in a solvent consisting of 7 parts of ethyl acetate and 1 part of ethanol, and then for 30 seconds in methanol to render the film whitely translucent. The film whose surface had thus been roughened when subjected to a discharge treatment in a stream of helium using a high frequency electrodeless discharge device (LTA type low temperature asher apparatus made by Tracerlab, U.S.A.). For comparison, a transparent polystyrene film whose surface had not been roughened in any way was subjected to the discharge treatment under the same conditions.

Pressure 10 mmHg Flow rate of helium gas cc/min. Output 50 W Discharge frequency 13.56 MHz A silver halide photographic emulsion of the follow ing formulation was coated on each of the resulting film bases. The amounts indicated below were those per m of the film.

Silver chlorobromide 3.5 g Gelatin (binder) 13.0 g Formalin (hardening agent) 0.1 g Saponin (wetting agent for coating) 0 03 g Water up to cc Each of the emulsion-coated films (photographic materials) was subjected to the peeling test, and the results are shown in Table i. (see attached sheet for Table l TABLE I Peel SIl'QIlgIll (ll/mm) Discharge Angle of contact against water Surface-roughened Transparent polystyrene treatment polystyrene film film Time Surace-roughened Transparent Dry Wet Dry Wet (seconds) polystyrene film Polystyrene Condition Condition Condition Condition film 82 87 0 0.0 0.0 0.0 (non-treated) It is seen from the results shown in Table 1 that when not subjected to the electrodeless discharge, both the transparent polystyrene films and the surfaceroughened polystyrene films hardly exhibited any bond strength with the coating of the galatin-silver halide emulsion. Even when subjected to the electrodeless discharge, the transparent polystyrene films did not show good adhesion. Table 1 clearly demonstrates that when the surface was roughened and subjected to the electrodeless discharge, biaxially drawn polystyrene films showed sufficiently good adhesion both in a dry condition and in a wet condition. The bond strength so obtained did not diminish, even after prolonged periods of time.

The results of this Example indicate that for imparting sufficient peel strength feasible as photographic materials, surface-toughening and high frequency electrodeless discharge treatment of polystyrene films are essential.

EXAMPLE 2 Pressure 10 mmHg Flow rate of oxygen 10 cc/min. Output 50 W Frequency 13.56 MHz Discharge treatment time 10. 30 and 60 seconds An aqueous gelatin solution of the following formulation was coated on the treated film as an undercoat.

lngredients Amts. per m of the film Gelatin (undercoat layer 10 g.

component) Formalin (20% aqueous solution 4 cc.

as hurdner) Water 190 cc.

A silver halide photographic emulsion of the same formulation as set forth in Example 1 was coated on top of the undercoat. Each of the resulting photographic materials exhibited good bond strength of 3.5 g/mm or more in a wet condition and 20 g/mm or more in a dry condition. The adhesion obtained between the film and the coatings was extremely good.

On the other hand, when the above gelatin solution was coated on a surface-roughened polystyrene film without subjecting the film to the high frequency electrodeless discharge treatment, the adhesion between the film and the gelatin coating was poor.

EXAMPLE 3 A 0.2 mm thick biaxially drawn polystyrene film was immersed in a solvent consisting of 1 part of acetone and 1 part of methyl ethyl ketone for 3 seconds, and then in methanol for 30 seconds to form a white translucent polystyrene film having a microporous surface layer (surface-roughened). The surface-roughened film was subjected to the high frequency electrodeless discharge treatment under the same conditions as set forth in Example 2. Thereafter, a coating solution for forming an image-receiving layer in the silver salt diffusion transfer process was coated on the polystyrene film so treated. The coating solution had the following formulation:

Ingredients Amts. per m of the film Gelatin (binder) 3 g Silver sulfide colloid (nucleus of development) 0.001 g Phcnylmercaptotetrazole (toning agent) 0.01-g Saponin (wetting agent) 002 g EXAMPLE 4 Pressure 10' mmHg Flow rate of helium 200 cc/min.

Output 50 W Discharge frequency 13.56 MHz Treating time 10, 30 and 60 seconds A silver halide color photographic emulsion having the following formulation was coated on the film:

Amts. Ingredients per m of film Silver chloridebromide 3,0 g. Gelatin 3.5 g. Emulsion containing benzoylaceto- 2-chloro-5-dodecyloxy-carbonylanilide (yellow coupler) 14.9 g. Triethylene phosphamide (3% acetone solution) 3.0 ml. Polyvinyl pyrrolidone 0.7 g

When the peel test was performed on the resulting color emulsion-coated film, it was found to have sufficient bond strength under any conditions, both in a dry condition and in a wet condition which is required for a color photographic material.

On the other hand, when the above-mentioned silver halide color photographic emulsion was coated on a surface-roughened polystyrene film support without subjecting it to the high frequency electrodeless dis charge treatment, the adhesion between the film and the coating proved to be very poor.

Although the present invention has been adequately described in the foregoing specification and examples included therein, it is readily apparent that one of ordinary skill in the art may make various changes and modifications thereon without derparting from the spirit and scope thereof.

What is claimed is:

1. A process for producing a photographic material,

which comprises subjecting a biaxially drawn. surfaceroughened polystyrene film to a high frequency electrodeless discharge treatment at a reduced pressure sufficiently low to sustain a glow discharge. and subsequently coating an aqueous composition of an emulsion on suspension containing gelatin as the binder onto said film.

2. The process of claim 1, wherein said high frequency electrodeless discharge treatment is performed in a vacuum of no more than 0.1 mmHg and at a frequency of 13.56 MHz.

3. The process of claim 1 wherein said electrodeless discharge treatment is performed in a stream of a member selected from the group consisting of oxygen and an inert gas.

4. The process of claim 1, wherein said surfaceroughened polystyrene film is obtained by treating a biaxially' drawn polystyrene film with an organic solvent capable of dissolving or swelling said film.

5. The process of claim 1, wherein said polystyrene film contains a white pigment.

6. The process of claim 1, wherein the coating of said composition is an undercoat of which a photographic emulsion is coated.

7. The process of claim 1 wherein the surfaceroughened polystyrene film surface, prior to said electrodeless discharge treatment, has a contact angle against water of about to and wherein said surface, after being subjected to said high frequency electrodeless discharge treatment, is strongly hydrophilic and has a contact angle against water of from 0 to 40.

8. The process of claim 1, wherein said polystyrene film contains a colored pigment.

9. The process of claim 3, wherein said gas stream flows at a rate of no more than cc/min.

10. The process of claim 3, wherein said inert gas is helium.

11. The process of claim 4, wherein said organic solvent is a member selected from the group consisting of tetrahydrofuran, methyl acetate, ethyl acetate. acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl chloride, ethylene chloride, cyclohexane. benzene and dimethylformamide and mixtures of same.

12. The process of claim 5, wherein said white pigment is a member selected from the group consisting of titanium dioxide, barium sulfate, calcium sulfate, barium carbonate. lithopone, alumina white, calcium carbonate, silica white, laolin. white lead, barite powder, flowers of zinc, talc, aluminum hydroxide and lime- 

2. The process of claim 1, wherein said high frequency electrodeless discharge treatment is performed in a vacuum of no more than 0.1 mmHg and at a frequency of 13.56 MHz.
 3. The process of claim 1 wherein said electrodeless discharge treatment is performed in a stream of a member selected from the group consisting of oxygen and an inert gas.
 4. The process of claim 1, wherein said surface-roughened polystyrene film is obtained by treating a biaxially drawn polystyrene film with an organic solvent capable of dissolving or swelling said film.
 5. The process of claim 1, wherein said polystyrene film contains a white pigment.
 6. The process of claim 1, wherein the coating of said composition is an undercoat of which a photographic emulsion is coated.
 7. The process of claim 1 wherein the surface-roughened polystyrene film surface, prior to said electrodeless discharge treatment, has a contact angle against water of about 80* to 90*and wherein said surface, after being subjected to said high frequency electrodeless discharge treatment, is strongly hydrophilic and has a contact angle against water of from 0* to 40*.
 8. The process of claim 1, wherein said polystyrene film contains a colored pigment.
 9. The process of claim 3, wherein said gas stream flows at a rate of no more than 100 cc/min.
 10. The process of claim 3, wherein said inert gas is helium.
 11. The process of claim 4, wherein said organic solvent is a member selected from the group consisting of tetrahydrofuran, methyl acetate, ethyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl chloride, ethylene chloride, cyclohexane, benzene and dimethylformamide and mixtures of same.
 12. The process of claim 5, wherein said white pigment is a member selected from the group consisting of titanium dioxide, barium sulfate, calcium sulfate, barium carbonate, lithopone, alumina white, calcium carbonate, silica white, laolin, white lead, barite powder, flowers of zinc, talc, aluminum hydroxide and limestone. 